title: Near-infrared dye-loaded PLGA nanoparticles prepared by spray drying for photoacoustic applications.
abstract: BACKGROUND
  Nanoparticulate contrast agents are of great interest for diagnostic applications with high resolution in medicine. Here we present polymer-based degradable nanoparticles exhibiting a near infrared (NIR) absorption suitable for photoacoustic imaging.
  
  
  METHODS
  The nanoparticles were prepared by incorporation of indocyanine green (ICG) as NIR dye in poly[(rac-lactide)-co-glycolide] (PLGA) via an optimized spray drying process. By application of a multi-step centrifugation protocol, two different size fractions were achieved. The biocompatibitilty of the nanoparticles was tested in 2D cell cultures (human hepatocarcinoma cells and monkey kidney cells) using WST-1, BrdU and LDH assay.
  
  
  RESULTS
  Spherical particles were obtained with a good yield (>81%), showing a high NIR-dye encapsulation efficiency (>98%). By multi-step centrifugation, two different size fractions with a mean diameter of 640 nm and 390 nm were obtained. Cytotoxicity studies of the synthesized ICG-loaded PLGA particles were performed. No cytotoxic effect on metabolic activity, proliferation, or membrane integrity was observed.
  
  
  CONCLUSIONS
  The high optical absorption at the relevant NIR-wavelength around 800 nm in combination with absence of cytotoxicity qualifies the ICG-loaded PLGA particles as promising candidates for degradable photoacoustic contrast agents.
authors.affiliation: Fraunhofer Institute for Biomedical Engineering, St Ingbert, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Kohl
authors.forename: Christian
authors.initials: C
authors.lastname: Kaiser
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bost
authors.forename: Frank
authors.initials: F
authors.lastname: Stracke
authors.forename: Hagen
authors.initials: H
authors.lastname: Thielecke
authors.forename: Christian
authors.initials: C
authors.lastname: Wischke
authors.forename: Andreas
authors.initials: A
authors.lastname: Lendlein
authors.forename: Karl
authors.initials: K
authors.lastname: Kratz
authors.forename: Robert
authors.initials: R
authors.lastname: Lemor
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D004396:Coloring Agents / Q000737:chemistry* / Q000633:toxicity; D003287:Contrast Media / Q000737:chemistry* / Q000633:toxicity; D004734:Energy Metabolism / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D007208:Indocyanine Green / Q000737:chemistry* / Q000633:toxicity; D053758:Nanoparticles; D010316:Particle Size; D011098:Polyglactin 910 / Q000737:chemistry* / Q000633:toxicity; D019265:Spectroscopy, Near-Infrared; D013499:Surface Properties; D014709:Vero Cells
chemical_list: D004396:Coloring Agents; D003287:Contrast Media; D011098:Polyglactin 910; D007208:Indocyanine Green